Apparatus for mixing fluids



Jung 18, 1940.- E w GARD r AL 2,205,089

APPARATUS FOR MIXING FLUIDS Filed July 5, 1938 3 Sheets-Sheet 1INVENTORS Blair @Aldrz'dge BY A TTORNEY.

Elar'le W. Gard &

June 18, 1940. w G ET AL 2,205,089

APPARATUS FOR MIXING mums Filed July 5, 1958 s Sheets-Sheet 2 INVENTORSEarle W. Gard & Blazr 6.,4Idrz'd 6 BY A TTORNEY- June 18, 1940. E, w, mmH M 2,2059% APPARATUS FOR MIXING FLUIDS Filed July 5. 1938 3Sheets-Sheet 3 I l 25 80 l 32 (i 23 f l k 97 21 E Z are a2" 32 103 BYBlair aAzrze Patented June 18, 1940 UNITED STATES 2,205,089 APPARATUS"roa mxmo rooms PATENT OFFICE Application July 5, 1938, Serial No.217,452

4 Claims.

The present invention relatesto the treatment of petroleum products, andhas particular reference to the production of high grade asphaltproducts suitable for any of the various uses in the art. Morespecifically, the invention pertains to certain improvements in aprocess and apparatus to be employed in the preparation of high gradeasphaltic products.

The use of air, gas and/or steam in varying proportions to oxidizepetroleum fractions has been used for many years. By varying theseproportions of air or steam, the yield of the oxidized asphalt thusproduced may be controlled to a limited degree. However, in order toobtain asphalts of a high melting point and having a high ductility anda desired penetration, it is necessary to produce an intimate mixture ofthe oil to be oxidized and of the oxygen containing gas, such as air orsteam, so that all parts or the oil are uniformily exp sed to the actionof the gas. Such intimate contact 'of the gas with the oil to beoxidized is also essential because it permits sufficient use of theoxygen-content of the gas and because such intimate contact permits theoxidation of the more refractory components of the oil.

The oxidation reaction, being exothermic in nature, an increase intemperature occurs during the reaction. It has therefore been foundessential to provide heat-abstracting means to control the temperatureand to prevent overoxidation. These heat-abstracting means are necessarysince the effect of oxidation, being exothermic, actually heats the oil,this increase in temperature, occurring even when the air is injected inthe cold or unheated state, for in the majority of cases the heat ofoxidation of 011 more than ofisets the cooling effect of the injectedcold air.

In an attempt to control the desired oxidation it has been previouslyproposed: to maintain the. oil to be oxidized in a heated stilloptionally provided with agitators; to main the air, steam or otheroxygen containing gases in the still above the oil therein; to controlthe temperature of the into the oil mass wherein the air is separatedfrom the oil; The repeated and continuous recycling of the oil from thestill, into the mixing or commingling zone, and back into the still(wherein optimum temperatures are controllably maintained as byheat-abstracting means) gradually oxidizes the oil until the desireddegree of oxidation has been attained.

We have previously described and patented processes for oil oxidationgand particularly for the production of oxidized asphalts, in which theintimacy and duration of contact of the asphaltic oil and oxygen havebeen controlled, and in which the temperature of the mixture is alsoregulable. These patents are: No. 1,953,345, No. 1,953,346, No.1,999,018. We have also described an improved process and apparatus orstructure in which the rates of introduction of asphaltic oil and of airinto the agitating zone, and the degree of agitation therein have beencontrolled to produce optimum oxidation, and in which the excessvelocity head over and above that necessary for the intimate agitation,is extracted from the mixture prior to the return of the mixture intothe still. For this purpose this excess velocity head is transformedinto energy which is used for the recirculation of the asphaltic oilbeing oxidized. This has been described and claimed in our co-pendingapplication Serial No. 74,264, filed April 14, 1936, (Patent 2,170,496,dated August 22, 1939) the present application being acontinuation-in-part of the aforementioned co-pending application.

It is an object of the present invention to provide a structure whichwill comprise improvements on the processes and apparatuses of the aboveapplication and patents, as wellas on all other processes of oxidation,reduction or chemical or physical interaction of oil, whether petroleum,animal or vegetable, or of other organic liquids in which it is desiredto produce an intimate commingling of the liquid and of the reactinggases.

It is a further object of this invention to provide a structure adaptedto withdraw continuously a measured quantity of oil or other liquid froma bulk supply such as a still, to admit continuously a measured streamof air or other gases'into the oil thus withdrawn, to commingleintimately the particles of such liquid and gas, and to return ordischarge said mixture back into the still wherein the gases areseparated from the liquid. It is a still further object of thisinvention to provide an improved structure to perform all of the aboveenumerated functions without the necessity of imparting to either theliquid or to the gas, or to both, any excessive velocities. It is astill further object of this invention to provide a structure whereinthe aforementioned commingling of the liquid and gas is realized atrelatively low velocities and/or pressure heads, and without excessiveagitation.

It is a still further object of the invention to provide a structureadapted to continuously withdraw a measured quantity of oil or otherliquid from a bulk supply, such as a still, to impart to the liquid thuswithdrawn a relatively low velocity and/or pressure head, to admitcontinuously and at a relatively low pressure a measured stream of airor other gases into the oil thus withdrawn, to commingle intimately andcontinuously the particles of such oil and gas without imparting theretoany excessive degree of agitation, and to return said mixture into thestill or bulk supply wherein the gases are separated from the liquid.Another object includes the provisionof means adapted to prevent orgreatly decrease the vibration of the described structure, thisvibration being ordinarily caused by the velocity, pressure head and/orsurging of the discharging mixture.

The above and other objects may be obtained by providing a structurecomprising a housing provided with oil and gas inlets, means in saidhousing adapted to suck a stream of oil continuously into said housing,means within the said housing adapted to intimately commingle said oilwith the gas introduced through the gas inlet, and discharge means forthe thus produced mixture. More specifically, the invention comprises apumping and agitating structure including a housing, means adapted tointroduce a stream of oil into said housing, means within said housingadapted to introduce a stream of air into said housing, means withinsaid housing adapted to intimately commingle said fluids withoutimparting thereto any excessive degree of agitation, and means for thedischarge of the thus obtained mixture out of said housing.

The invention still further includes a structure wherein the abovementioned means for introducing the oil into the structure are adjustedto regulate and control the velocity and/or pressure head imparted tosuch oil.

The invention still further includes a structure of the characterhereinabove in combination with means for preventing any vibration ofthe structure which may be caused by the velocity, pressure and/orsurging of the discharging mixture, said means including arcuated meansadapted to receive the discharging mixture and to return said mixture tothe bulk supply in the still.

In one of its specific embodiments, the invention resides in a fluidmixing structure including a motor, a rotary shaft driven by said motor,a rotary fluid pump or propeller mounted on said shaft adapted toreceive and discharge a fluid at a relatively low velocity head, ahousing around said propeller said housing being provided with a fluidinlet through which the fluid may be conveyed to the propeller, meanswithin said housing and adjoining the discharge phase of said propelleradapted to cause the fluid to flow in a direction substantially parallelto the axis of the pump, means communicating with said housing andadapted to convey thereto a gas, means within said housing andsubstantially adjacent to the discharge end of the last mentioned meansadapted to intimately commingle said fluid and gas thus introduced intothe housing and means adapted to discharge said mixture.

Additional objects, as well as the various particulars of the presentinvention will become apparent from a discription of the accompanyingdrawings, in which:

Fig. 1 illustrates a. vertical sectional view. partly in elevation, ofacirculating pump and mixing structure built and assembled according tothe present invention;

Fig. 9 illustrates a fragmentary vertical sectional view, partly inelevation, of a modified embodiment of the invention, this embodimentproviding means for discharging the mixture back into the still andsimultaneously preventing or decreasing any vibration of the pumpstructure which may be caused by the velocity and pressure of thedischarge mixture.

Fig. 10 is a section taken along line Ill-l0 of 9;

Fig. 11 is a diagrammatic view, partly in elevation and partly inlongitudinal section through a still equipped with a vertically disposedpumping and mixing structure of the type shown in Fig. 1; and

Fig. 12 is a section taken along line |2|2 of Fig. 11.

Referring now to the drawings and more particularly to Fig. l and thesections shown in Figs. 2 to 8, inclusive, the circulating andcommingling means are inclosed in a housing generally indi- I cated bynumeral 20. This housing consists of two sections 2| and 22 which arebolted or otherwise united as at 23. These sections are generallyannular in shape but have various constructions described in greaterdetail herein below. The housing 20 is suspended from a supporting pipe25, the upper end of which is attached to a plate 26, bolted orotherwise united to the upper end of a still 28 in which the assembly isdisposed.

A shaft 30 extends vertically through the diametric center of supportingpipe 25 and of the housing 20. The lower end of said shaft 3|) issupported at the lower end of section 2| by means of a bearing 3|.Section 2| is also provided with an annular opening 32 adapted tocommunicate the interior of section 2| with the outside. Within section2| and substantially in its upper portion, shaft 30 is provided with apumping device 34. As shown in Figs. 1 and 8, said pumping device may beof the impeller type consisting of a plurality of blades 35 attached toa hub 36 which is actuated by the rotation of shaft 30. For the purposeof attachment of blades 35, as well as to provide an impeller pump of avariable pitch type, the inner edges of blades 35 are equipped withbolts 31, these bolts passing through a hub 36 and being rigidlyattached thereto as by means of nuts 38. It is thus clear that blades 35may be rotated on their bolts 31,

thereby regulating the pitch of the impeller pump 34.

The lower portion of section 22, immediately above the pumping device 34in section 2|, comprises a stator section more particularly shown inFig. 7, and adapted to force the upwardly moving liquid to flow in adirection substantially parallel to the axis of the pump. For thispurpose, this lower portion of section 22 is provided with a pluralityof radially disposed ribs 43 which extend between and are connected orotherwise attached to the inner walls of said section 22 and to astationary hub 42 arranged substantially adjacent to the shaft 36. Aplurality of vanes 4| are attached to said ribs 43. As stated, thepurpose of vanes 4| is to deflect the stream of liquid pumped upwardlyby impelled plates 35, and to cause said liquid to pass substantiallyvertically and axially with respect to the axis of the structure. Forthis purpose vanes 4| are curved or actuated as shown more specificallyin Fig. 7, the upper portions or ends of said vanes 4|, near theirjunction with ribs 43, being substantially vertical in configuration.

The upper part of section 22 is also provided with a plurality of ribs46. These ribs also extend radially, as this is shown in Fig. 5, andthey align with the upper edges of the aforementioned ribs 43. Ribs 46are however hollowed, providing a space 41 therein. This space 41communicates at 48 with an air-introducing pipe 46 extending axiallywithin supporting pipe 25 and around shaft 30. Ribs 46 are also providedwith a plurality of slots 5| communicating the interior 41 of said ribswith the space surrounding each of said ribs. Preferably, as shown moreparticularly in Fig. 6, these openings or slots 5| are drilled at anangle so that the air or other oxygen-containing gases, passing fromspace 41 outwardly, is ejected in an upwardly direction.

The upper end of section 22 is enclosed'by a webbed plate 54, webs 55 ofwhich are connected to the supporting pipe 25. To facilitate thedischarge of the air-liquid mixture, the lower portion of said pipe isprovided with ports or openings 56. Optionally and only for the purposeof strengthening the structure supporting elements 51 connect with web55 to pipe 25 on the two sides wherein pipe 25 is provided with theaforementioned ports 56.

As indicated in Fig. 1, the upper end of airpipe 49 passes through plate26 and communicates with a curved pipe or elbow 6|! which terminates ina flange 6|. Shaft 30 passes through said curved pipe 60 and through apacking gland 62, the upper end of shaft 36 being attached directly orotherwise to shaft 63 of an actuating motor 64 supported by means 65 tothe plate 26.

As shown in the drawings, the pumping, circulating and comminglingstructure described hereinabove is disposed in still 28, the lower endof the structure being supported substantially at the lower end of thestill as by means 66 which are rigidly attached as at 61 to the bottomof still 28. This support is for the purpose of preventing the swingingof the structure during the actuation of the pump.

In operation, shaft 30 is rotated by motor 64 in the direction shown bythe arrow (see Fig. l). The pumping device of impeller 34 actuated bythe rotation of shaft 30 causes the upward flow of the oil or otherliquid entering section 2| through opening 32. By varying the pitch orangle of blades it is possible to regulate the rate of inflow of theliquid into housing 26. The

liquid thus pumped upwardly by the impeller 34 enters the lower portionof section 22, wherein it is forced to pass along the arcuated surfacesof blades or vanes 4|. Due to the curvature of these vanes 4|, theupwardly moving liquid is gradually forced to move in a path which isparallel to the axis of the pumping structure. Therefore, when thestructure is disposed vertically, as shown in Fig. l, the liquid beinglifted by the pump or impeller 34, will be flowing in a substantiallyvertical direction when it enters the upper part of section 22. Duringsuch passage through said upper part of section 22, the oil movesupwardly between the hollow ribs 46. Simultaneously, air or a similaroxygen-containing gas is conveyed downwardly through pipes 60 and 49,this air passing through the openings 48 into the interior 41 of thehollow ribs 46. This air then passes from 41 through ports 5| into thisspace between the ribs 46, thus coming into contact and commingling withthe upwardly moving stream of liquid. Because of the slanting or angularposition of ports 5|, the air is caused to move upwardly andsubstantially in the direction of the flow of the liquid, thus aiding inthe lifting of said liquid. The liquid-air mixture thus formed thenpasses through webbed plate 54 (between the webs 55) and, after passingthrough openings or ports 56 in the lower portion of pipe 25, overflowsinto the still from which the liquid was originally withdrawn throughopening 32.

It is thus seen that the liquid, such as for example an asphaltic oil tobe oxidized, may be continuously recirculated or recycled through theabove described structure, each particle of this oil coming into contactwith air introduced through ports 5|, and the mixture thus formedoverflowing back into the still wherein the oil separates from the air.The provision of the straightening vanes 4! and the introduction of theair through ports 5| in ribs 46 eliminates any excessive agitation. Ithas been found. however, that there is sufficient commingling betweenthe oil and the air to cause the necessary interaction or oxidation ifan asphaltic oil is to be oxidized. Since no excessive agitation isnecessary and because of the relatively short lift to which the oil isto be subjected, there is a considerable saving in energy, the impellerpump imparting to the oil entering through opening 32 only sufiicientenergy and/or velocity to cause its upward movement through thestructure 26 and to a point just above the webbed plate 54. Anotheradvantage resides in the fact that the air can be introduced at a verylow pressure. Thus, the angular arrangement or disposition of ports 5|in ribs 46 permits the upwardly moving stream of oil to create a partialvacuum within the hollow ribs 46, thus aiding in the injection of theair into the oil to be oxidized. Obviously, the velocity and pitch ofthe impeller blades 35 can thus be regulated for each individual case,the liquid receiving only enough energy for its travel through thestructure. A further advantage of the present structure resides in thefact that the air inlet line is constructed and arranged so that it isnot necessary to work within the still when it is desired to remove thestructure, as for example when it is necessary to repair same. The axialdisposition of air conduit 49, as well as the provision of the bent pipeor elbow 60 and of flange 6|, permits the removal or withdrawal of thewhole structure by a simple disconnecting of the air-pipe at flange 6|.Obviously, plate 26, supporting the hollow structure must also bereleased from still 28 when such a withdrawal is contemplated.

Figs. 9 and 10 disclose a modified embodiment of the structure. Thepumping and agitating structure employed in this apparatus is identicalto the one shown in Figs. 1 to 8 and described hereinabove. The onlymain difference between the two structures resides in the provision ofcertain discharge means which prevent or at least greatly inhibit thevibration of the apparatus, this vibration being caused by the surgingand the force of the mixture discharging from the mixing agitatingapparatus.

As shown more specifically in Fig. 9, the mixing and pumping apparatusis the same as that shown in Figs. 1 to 8. Thus, actuating motor 64 issupported by means 65 on plate 26 which is bolted or otherwise united tothe upper end of still 28. Shaft 30 is directly attached to shaft 63 ofthe motor and passes downwardly and into still 28 through packing gland62. At its lower end shaft 30 extends into housing 20 containing thepumping and agitating stretcher more fully described hereinabove. Thehousing 20 is suspended on pipe 25 the upper end of which is attached tothe aforementioned plate 26. The air or similar gas is introducedthrough the concentric pipe 49 the upper end of which passes throughplate 26 and communicates with a curved pipe or elbow 60 terminating ina connecting flange 6|.

Instead of providing the discharge openings 56 in pipe 25 substantiallyimmediately above housing 20, the modified embodiment discloses thatsaid discharge opening from pipe 25 is provided near the upper end ofpipe 25. For this purpose a curved or arcuated travel plate II isdisposed within said pipe 25 and around the air introducing pipe 49. Onone side pipe 25 is provided with a discharge opening I2, baffle IIbeing preferably curved so as to permit a gradual change in direction offlow of the discharging mixture. For the purpose of dissipating theenergy or velocity of the mixture thus discharged through opening 12 andfor the purpose of facilitating the separation of the liquid from thegas, an arcuated plate 13 is attached to the side of the dischargeopening I2. Preferably the plate is arcuated in the form of a spiral sothat the discharging flu d is gradually caused to reverse its directionof flow, as more fully shown in Fig. 10. For purposes of stability andsupport, plate I3 is attached at 14 and 15 to the sides of still 28 and16 to a supporting beam 11.

The advantage of the embodiment shown in Figs. 9 and 10 resides in thefact that the mixture discharged upwardly through pipe 25 is returnedinto the still above the oil level therein. Also the provision of thearcuated plate 13 prevents any excessive vibration of the mixing andagitating structure.

Figs. 10 and 11 disclose an embodiment in which a pumping andeommingling structure of the type shown in Figs. 1 to 8 is employed foroxidizing an asphaltic oil. In these figures a still 80, provided withthe usual man-hole 8|, is disposed horizontally on a brickwork 83 of afurnace 84. This furnace, equipped with a burner 85 connected to asource of fuel not shown in the drawings. The flue gases from thefurnace 84 are discharged through opening 86. To cause the products ofcombustion to fiow along the lower and side walls or still 80, thefurnace may be provided with a bafiie wall 81. At one of its ends, still80 is provided with oil inlet 89, while asphalt discharge pipe may beprovided at the other end of said still and preferably at its lowerside. If desired, the still may be equipped with steam inlets as well aswith vapor discharge openings.

A commingling and pumping structure of the type described hereinabove isdisposed vertically within still 80 in such a manner that its actuatingmotor 64 is located outside of said still. As previously described, thismotor is supported on a base-plate 26 by means 65, said base-plate beingbolted or otherwise attached to the upper wall of still 80. Pipe 93,equipped with valve 94 is attached to flange 6| of the air-introducingpipe more fully described hereinabove in connection with the descriptionof Figure 1. Regulation of valve 94 thus controls the rate of input ofair or other oxygen-containing gases. Pipe 25, supporting the housing20, extends downwardly from plate 26 so that said housing 20 enclosingthe housing and commingling units of this structure) is located withinthe oil 91 being oxidized. Although ports 56 adapted to discharge theair-oil mixture back into the still are shown to be below level 98 ofthe oil being oxidized, it is obvious the structure may be located sothat the oil-air mixture may be discharged above said level. The oilinlet 32 opens into a space I00 formed by a baffle IOI extendinghorizontally across the lower portion of the still and substantially,but not quite, the length thereof. This space I00 is closed at one endby baffle I02, the other end I03 being open and communicating with therest of the interior of still 80. This still is also provided withheating or cooling coils I05 adapted to control the temperature of theoil being oxidized. This heating or cooling medium enters coils I05through pipe I06 and leaves said coil through I01.

In operation, the oil to be oxidized and maintained at a propertemperature by means of the coil I05 and of the furnace 84, is drawninto the pumping and commingling structure through opening 32. This iscaused by the impeller pump in section 2I, said pump being actuated bymotor 64. Simultaneously, air or a similar oxygencontaining gas isintroduced at a predetermined rate through pipe 93. The two fluidscommingle (as described hereinabove) in section 22 of the structure 20,the mixture returning back into the I still 80 through theaforementioned openings 56. If desired, the vapors and the spent gasesmay be withdrawn from still 80, as for example. through a vent linewhich may be attached to or provided on the man-hole or dome 8|. visionof baffle means IOI and I02 prevents the oil from entering therecirculating structure 20 except by first passing through space I00separated from the rest of the still by said baffling means. It is thusobvious that a current is created in the still, the oil to be oxidizedbeing forced across the whole length of the still prior to the time whensaid oil enters through I03 into the space I00 and then through opening32 into the pumping and commingling structure described herein. Theprovision of these baffling means (as well as of the current thereby)aids a thorough separation of the gas or air from the mixture thereofwith the oil coming out from the commingling zone through opening 56.The provision of these means also aids a thorough commingling of the oilbeing oxidized thus permitting a uniform oxidation of all of the oil instill 80.

It is obvious that the oil in said still 80 should The pro- Sit beinitially heated to the oxidation temperature, after which the abovedescribed oxidation process could be started. Thereafter, coil "15 maybe used to control the temperature of the oil in the still during theoxidation thereof. In most cases, due to the fact that the oxidationreaction is exothermic in nature, a cooling means will have to becirculated through coil I05 to abstract the excess heat generated instill 80 during this oxidation of the oil.

Although the drawings and the operation of the structures shown thereinare described as used for the oxidation of petroleum or asphaltic oils,it is obvious that said structures may also be employed for comminglingand agitating any other liquids with gases.

While the invention has been herein disclosed in what is now consideredto be the preferred form, it is to be understood that the invention isnot limited to the specific details thereof, but covers all changes,.modifications and adaptations within the scope of the appended claims.

We claim:

1. A fluid mixing apparatus including a motor, a rotary shaft driven bysaid motor, a casing around said shaft, a rotary fluid propeller mountedon the end of said shaft and within said casing and adapted to receive afluid and to discharge it into said casing at a relatively low velocityhead, arcuated vanes within said casing and adjacent the discharge sideof said propeller adapted to cause the fluid to flow in a directionsubstantially parallel to the axis of said shaft and casing, and aplurality of hollow ribs disposed radially with respect to the axis ofthe shaft, said ribs being provided withv openings communicating theinterior of said hollow ribs with the exterior thereof.

2. A fluid mixing apparatus including a motor, a rotary shaft driven bysaid motor, a casing around said shaft, a rotary fluid propeller mountedon the end of said shaft and within said casing and adapted to receive afluid and to discharge it into said casing at a. relatively low velocityhead, arcuated vanes within said casing and adjacent the discharge sideof said propeller adapted to cause the fluid to flow in a directionsubstantially parallel to the axis of said shaft and casing, and aplurality of hollow ribs disposed radially with respect to the axis ofthe shaft, and openings in the sides of said ribs communicating theinterior of said hollow ribs with the exterior thereof, said openingsbeing disposed at an angle with respect to the sides of said ribs,whereby the second fluid is introduced from the interior of said ribsthrough said openings and into the first fluid substantially parallel Qto the axis of the shaft, thereby aiding in the moving of the firstfluid and also causing said fluids to be intimately commingled.

3. A fluid mixing apparatus including a tank adapted to receive amixture of fluids, a motor mounted on said tank, a rotary shaft drivenby said motor and extending into said tank, a rotary fluid propellermounted on said shaft near the lower end thereof and adapted to receivea fluid and to discharge it at a relatively low velocity head, astationary casing adapted to receive said fluid, arcuated vanes withinsaid casing and disposed radially with respect to the pump shaft andadapted to receive said fluid and to cause it to move substantiallyvertically and parallel to the axis of said shaft, a fluid inlet pipeaxially disposed around the pump shaft, a plurality of radially arrangedhollow ribs communicating with said pipe, and openings in the sides ofsaid ribs communicating the interior of said hollow ribs with theexterior thereof, said openings being disposed at an angle with respectto the sides of said ribs whereby the second fluid is introduced fromsaid pipe and the interior of said ribs through said openings and intothe first fluid substantially parallel to the axis of the shaft, anddischarge means adapted to discharge the mixed fluids into said tank forrecirculation.

4. A fluid mixing apparatus including a tank adapted to receive amixture of fluids, a motor mounted on'said tank, a rotary shaft drivenby said motor and extending into said tank, a rotary fluid propellermounted on said shaft near the lower end thereof and adapted to receivea fluid and to discharge it at a relatively low velocity head, astationary casing adapted to receive said fluid, arcuated vanes withinsaid casing and disposed radially with respect to the pump shaft andadapted to receive said fluid and to cause it to move substantiallyvertically and parallel to the axis of said shaft, a fluid inlet pipeaxially disposed around the pump shaft, a plurality of radially arrangedhollow ribs communicating with said pipe, and openings in the sides ofsaid ribs communicating the interior of said hollow ribs with theexterior thereof, said openings being disposed at an angle with respectto the sides of said ribs whereby the second fluid is introduced fromsaid pipe and the interior of said ribs through said openings and intothe first fluid substantially parallel to the axis of the shaft, andwherein the discharge openings communicate with an arcuated bafliewithin the tank, said baflie being adapted to receive the dischargedfluids and to return said fluids into the tank without substantialvibration of the mixing apparatus, and discharge means adapted todischarge the mixed fluids into said tank for recirculation.

'EARLE W. GARD. BLAIR G. ALDRIDGE.

